v2writable: implement ->replace call

Much of the existing purge code is repurposed to a general
"replace" functionality.

->purge is simpler because it can just drop the information.
Unlike ->purge, ->replace needs to edit existing git commits (in
case of From: and Subject: headers) and reindex the modified
message.

We currently disallow editing of References:, In-Reply-To: and
Message-ID headers because it can cause bad side effects with
our threading (and our lack of rethreading support to deal with
excessive matching from incorrect/invalid References).

1 files changed, 199 insertions, 0 deletions

diff --git a/t/replace.t b/t/replace.t
new file mode 100644
index 00000000..6fae5511
--- /dev/null
+++ b/t/replace.t
@@ -0,0 +1,199 @@
+# Copyright (C) 2019 all contributors <meta@public-inbox.org>
+# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
+use strict;
+use warnings;
+use Test::More;
+use PublicInbox::MIME;
+use PublicInbox::InboxWritable;
+use File::Temp qw/tempdir/;
+require './t/common.perl';
+require_git(2.6); # replace is v2 only, for now...
+foreach my $mod (qw(DBD::SQLite)) {
+        eval "require $mod";
+        plan skip_all => "$mod missing for $0" if $@;
+}
+
+sub test_replace ($$$) {
+        my ($v, $level, $opt) = @_;
+        diag "v$v $level replace";
+        my $this = "pi-$v-$level-replace";
+        my $tmpdir = tempdir("$this-tmp-XXXXXX", TMPDIR => 1, CLEANUP => 1);
+        my $ibx = PublicInbox::Inbox->new({
+                mainrepo => "$tmpdir/testbox",
+                name => $this,
+                version => $v,
+                -primary_address => 'test@example.com',
+                indexlevel => $level,
+        });
+
+        my $orig = PublicInbox::MIME->new(<<'EOF');
+From: Barbra Streisand <effect@example.com>
+To: test@example.com
+Subject: confidential
+Message-ID: <replace@example.com>
+Date: Fri, 02 Oct 1993 00:00:00 +0000
+
+Top secret info about my house in Malibu...
+EOF
+        my $im = PublicInbox::InboxWritable->new($ibx, {nproc=>1})->importer;
+        # fake a bunch of epochs
+        $im->{rotate_bytes} = $opt->{rotate_bytes} if $opt->{rotate_bytes};
+
+        if ($opt->{pre}) {
+                $opt->{pre}->($im, 1, 2);
+                $orig->header_set('References', '<1@example.com>');
+        }
+        ok($im->add($orig), 'add message to be replaced');
+        if ($opt->{post}) {
+                $opt->{post}->($im, 3, { 4 => 'replace@example.com' });
+        }
+        $im->done;
+        my $thread_a = $ibx->over->get_thread('replace@example.com');
+
+        my %before = map {; delete($_->{blob}) => $_ } @{$ibx->recent};
+        my $reject = PublicInbox::MIME->new($orig->as_string);
+        foreach my $mid (['<replace@example.com>', '<extra@example.com>'],
+                                [], ['<replaced@example.com>']) {
+                $reject->header_set('Message-ID', @$mid);
+                my $ok = eval { $im->replace($orig, $reject) };
+                like($@, qr/Message-ID.*may not be changed/,
+                        '->replace died on Message-ID change');
+                ok(!$ok, 'no replacement happened');
+        }
+
+        # prepare the replacement
+        my $expect = "Move along, nothing to see here\n";
+        my $repl = PublicInbox::MIME->new($orig->as_string);
+        $repl->header_set('From', '<redactor@example.com>');
+        $repl->header_set('Subject', 'redacted');
+        $repl->header_set('Date', 'Sat, 02 Oct 2010 00:00:00 +0000');
+        $repl->body_str_set($expect);
+
+        my @warn;
+        local $SIG{__WARN__} = sub { push @warn, @_ };
+        ok(my $cmts = $im->replace($orig, $repl), 'replaced message');
+        my $changed_epochs = 0;
+        for my $tip (@$cmts) {
+                next if !defined $tip;
+                $changed_epochs++;
+                like($tip, qr/\A[a-f0-9]{40}\z/,
+                        'replace returned current commit');
+        }
+        is($changed_epochs, 1, 'only one epoch changed');
+
+        $im->done;
+        my $m = PublicInbox::MIME->new($ibx->msg_by_mid('replace@example.com'));
+        is($m->body, $expect, 'replaced message');
+        is_deeply(\@warn, [], 'no warnings on noop');
+
+        my @cat = qw(cat-file --buffer --batch --batch-all-objects);
+        my $git = $ibx->git;
+        my @all = $git->qx(@cat);
+        is_deeply([grep(/confidential/, @all)], [], 'nothing confidential');
+        is_deeply([grep(/Streisand/, @all)], [], 'Streisand who?');
+        is_deeply([grep(/\bOct 1993\b/, @all)], [], 'nothing from Oct 1993');
+        my $t19931002 = qr/ 749520000 /;
+        is_deeply([grep(/$t19931002/, @all)], [], "nothing matches $t19931002");
+
+        for my $dir (glob("$ibx->{mainrepo}/git/*.git")) {
+                my ($bn) = ($dir =~ m!([^/]+)\z!);
+                is(system(qw(git --git-dir), $dir, qw(fsck --strict)), 0,
+                        "git fsck is clean in epoch $bn");
+        }
+
+        my $thread_b = $ibx->over->get_thread('replace@example.com');
+        is_deeply([sort map { $_->{mid} } @$thread_b],
+                [sort map { $_->{mid} } @$thread_a], 'threading preserved');
+
+        if (my $srch = $ibx->search) {
+                for my $q ('f:streisand', 's:confidential', 'malibu') {
+                        my $msgs = $srch->query($q);
+                        is_deeply($msgs, [], "no match for $q");
+                }
+                my @ok = ('f:redactor', 's:redacted', 'nothing to see');
+                if ($opt->{pre}) {
+                        push @ok, 'm:1@example.com', 'm:2@example.com',
+                                's:message2', 's:message1';
+                }
+                if ($opt->{post}) {
+                        push @ok, 'm:3@example.com', 'm:4@example.com',
+                                's:message3', 's:message4';
+                }
+                for my $q (@ok) {
+                        my $msgs = $srch->query($q);
+                        ok($msgs->[0], "got match for $q");
+                }
+        }
+
+        # check overview matches:
+        my %after = map {; delete($_->{blob}) => $_ } @{$ibx->recent};
+        my @before_blobs = keys %before;
+        foreach my $blob (@before_blobs) {
+                delete $before{$blob} if delete $after{$blob};
+        }
+
+        is(scalar keys %before, 1, 'one unique blob from before left');
+        is(scalar keys %after, 1, 'one unique blob from after left');
+        foreach my $blob (keys %before) {
+                is($git->check($blob), undef, 'old blob not found');
+                my $smsg = $before{$blob};
+                is($smsg->{subject}, 'confidential', 'before subject');
+                is($smsg->{mid}, 'replace@example.com', 'before MID');
+        }
+        foreach my $blob (keys %after) {
+                ok($git->check($blob), 'new blob found');
+                my $smsg = $after{$blob};
+                is($smsg->{subject}, 'redacted', 'after subject');
+                is($smsg->{mid}, 'replace@example.com', 'before MID');
+        }
+        @warn = ();
+        is($im->replace($orig, $repl), undef, 'no-op replace returns undef');
+        is($im->purge($orig), undef, 'no-op purge returns undef');
+        is_deeply(\@warn, [], 'no warnings on noop');
+}
+
+sub pad_msgs {
+        my ($im, @range) = @_;
+        for my $i (@range) {
+                my $irt;
+                if (ref($i) eq 'HASH') {
+                        ($i, $irt) = each %$i;
+                }
+                my $sec = sprintf('%0d', $i);
+                my $mime = PublicInbox::MIME->new(<<EOF);
+From: foo\@example.com
+To: test\@example.com
+Message-ID: <$i\@example.com>
+Date: Fri, 02, Jan 1970 00:00:$sec +0000
+Subject: message$i
+
+message number$i
+EOF
+
+                if (defined($irt)) {
+                        $mime->header_set('References', "<$irt>");
+                }
+
+                $im->add($mime);
+        }
+}
+
+my $opt = { pre => *pad_msgs };
+test_replace(2, 'basic', {});
+test_replace(2, 'basic', $opt);
+test_replace(2, 'basic', $opt = { %$opt, post => *pad_msgs });
+test_replace(2, 'basic', $opt = { %$opt, rotate_bytes => 1 });
+
+SKIP: if ('test xapian') {
+        require PublicInbox::Search;
+        PublicInbox::Search::load_xapian() or skip 'Search::Xapian missing', 8;
+        for my $l (qw(medium)) {
+                test_replace(2, $l, {});
+                $opt = { pre => *pad_msgs };
+                test_replace(2, $l, $opt);
+                test_replace(2, $l, $opt = { %$opt, post => *pad_msgs });
+                test_replace(2, $l, $opt = { %$opt, rotate_bytes => 1 });
+        }
+};
+
+done_testing();